Antibiotics and antibacterial products have saved a countless number of lives. With all the good that antibiotics have brought to the world, an unforeseen problem has surfaced. As more antiobiotics are used, bacteria are adapting to the selective pressures imposed on them by humans. Natural selection has acted on bacteria, creating new strains (genetic variants of a species) of bacteria with mutations coding for antibiotic resistance.

The new strains produced from the subtle mutations in bacterial DNA over a short period of time can best be described as which type of evolution?

A. microevolution

B. macroevolution

C. artificial evolution

D. punctuated equillibrium